Pleocnemia nesiotica (Holttum) H.G. Zhao & S.Y. Dong, 2015

ZHAO, HUI-GUO & Dong, Shi-Yong, 2015, The true identity of Tectaria nesiotica Holttum (Tectariaceae), with comments on the species identification in Pleocnemia (Dryopteridaceae), Phytotaxa 202 (1), pp. 45-50 : 46

Pleocnemia nesiotica (Holttum) H.G. Zhao & S.Y. Dong , comb. nov. ( Figs. 1E , 2 )

Basionym:— Tectaria nesiotica Holttum (1991a: 553) .

Type:— PAPUA NEW GUINEA. Milne Bay: Goodenough Island (Kalimatabutabu), 9°19 ′ S, 150°15 ′ E, alt. 950 m, 19 Dec. 1977, J. Croft & J. Marsh LAE 71234 (holotype K-000375362 & K-000375363!, isotype LAE-236265!).

Morphology observations:—Rhizome erect, leaf 2 m long including stipe 0.8 m long (information from the field record by collectors); stipe black, glossy, nearly 10 mm in diameter; scales confined to the very base of stipe, narrow lanceolate, ca. 15–20 × 1.5 mm, dark brown, entire at margin; lamina 3-pinnatifid above base (the basal pinna not seen); middle pinna nearly oblong, sessile, ca. 40 × 17 cm, its base as the same wide as or slightly narrowed than the middle, bearing 18 pairs of free pinnules; pinnules alternate or subopposite on distal costae, sessile or very shortly stalked (1 mm), nearly linear, mostly in the same size, 7–8.5 × 1.5–2 cm, the distal 5 pairs of pinnules gradually shortened towards apex of pinna, all deeply lobed to the wing of costules (the wing ca. 1.2 mm wide on either side of costae); pinnule-lobes ca. 12 pairs, 8–10 × 2.5 mm, obtuse at apex, more or less crenate at margin, widely spaced from each other (the space ca. 3 mm wide between fertile lobes or 1–1.5 mm wide between the sterile ones); upper pinnae gradually shortened towards apex of lamina, 1-pinnate to 1-pinnatifid; rachis and costa black, glossy on abaxially surface, with copious short ctenitoid hairs on adaxial surface; veins forming a row of areole on either side of costule, others all free; sori rounded, on distal part of pinnule lobes, one row on either side of midrib of pinnule lobes, usually 2 or 3 pairs each lobe, adjacent each other when mature; indusia distinct, persistent or not.

Note:—This is a rather insufficiently known species, although the color of the axes and the position of the sori make it distinct from other species in Pleocnemia . For this species there is to date only one collection known to us, i.e., Croft & Marsh LAE 71234. Like most species in this genus, the frond of P. nesiotica is very big and its type collection was cut into several parts. We have seen four parts of the collection deposited in herbaria, two sheets (holotype) in K and two sheets (isotype) in LAE. Other parts were probably lost. To know more about P. nesiotica , further collections from its type location are needed.

Figures

FIGURE 1. Comparison of venation pattern between Tectaria (A–D) and Pleocnemia (E). For Tectaria the basal basiscopic veins of pinna lobes (or pinnule lobes) arise from costae (or correspondingly costules) but not from the midrib of lobes (A–D); while for Pleocnemia the basal basiscopic veins arise from the midrib of lobes (E).—A. Tectaria sagenioides based on Dong 1599 (IBSC).—B. T. devexa based on Dong 1500 (IBSC).—C. T. multicaudata based on Clarke 18427 (holotype, K).—D. T. griffithii based on Griffithii s.n. (holotype, K).—E. Pleocnemia nesiotica based on Croft & Marsh LAE71234 (holotype, K) (Drawn by S.Y. Dong).

FIGURE 2. Type specimens of Pleocnemia nesiotica.—A. Holotype at K-000375362.—B. Isotype at LAE-236265.—C. Detail of B, showing sinus teeth between lobes of pinnules (arrows pointing).